(1) Field of the Invention:
The present invention relates to a hot-melt adhesion process for vulcanized rubber.
(2) Description of the Prior Art:
When a vulcanized rubber compositiin is adhered to the same or different kind vulcanized rubber composition or a porous material, such as cloth, paper, leather, wood or the like, by a conventional hot-melt process, it is necessary to buff the surface of both the members. Moreover, it is troublesome to select properly a suitable kind of hot-melt adhesive depending upon the kind of the vulcanized rubber. Further, a satisfactorily high bonding strength can not always be obtained therefore a need exists to overcome these drawbacks.
The inventors have made various investigations in order to solve these drawbacks and found that, when a vulcanized rubber composition, whose rubber component contains syndiotactic-1,2-polybutadiene, is adhered to another member by the hot-melt process in the presence of a syndiotactic-1,2-polybutadiene thin film interposed between the surfaces of the members to be adhered very high adhesion can be obtained without previously carrying out troublesome step of buffing the surfaces.
Syndiotactic-1,2-polybutadiene is a thermoplastic resin having a melting point of 80.degree.-90.degree. C. and a low melt viscosity. Therefore, this resin has hitherto been used as a hot-melt adhesive for porous materials, such as paper, cloth, leather, wood and the like. The present invention aims to apply the hot-melt adhesion process by this resin to the bonding of vulcanized rubber composition.